1. Field of the Invention
The present invention relates to a matching device for a pair of images, which is used in photogrammetry.
2. Description of the Related Art
In conventional photogrammetry, two images containing a common object are photographed and input to a computer, where a detecting process is performed in which, on the surface of a monitor device, a designating point contained in one of the images is selected so that the corresponding point existing on the other image is detected. In the detecting process, the designating point is selected, and thus, first, a corresponding line which is a straight line containing the corresponding point is obtained in the other image. Then, from among the pixels positioned on the corresponding line, the pixel with the value closest to that of the designating point is extracted, as the corresponding point.
In the detecting process of the corresponding point, if the corresponding point is detected from the other image based on only a single designating point selected from the first image, there may be some pixels having pixel values which are close to the pixel value of the designating point, and therefore, the correct point may not be detected.
Therefore, a method is proposed in which predetermined (n×n) pixels close to the designating point are used to detect the corresponding point. Namely, in this method, regarding each point on the corresponding line, a correlation between pixel values of (n×n) pixels surrounding the point and pixel values of (n×n) pixels surrounding the designating point is considered. In this method, however, since a lot of pixels are processed, a problem occurs, in which the process time is long.